Air brake slack adjuster



I March 2, 1948. I E; L. BOWEN AIR BRAKE SLACK ADJUSTER Filed Feb. 20, 1946 2 SheeiS-Sheet 1 -NHW w INVENTOR.

. Q I y B 'dward L.Bowe w/ flzfirne s March 2, 1948. E. BOWEN AIR BRAKE SLACK ADJUSTER Filed Feb. 20, 1946 2 Sheets-Sheet 2 INVENTOR.

Edward lLBowew Patented Mar. 2, i948 UNITED T PATENT OF F 1 CE 'AIRBRAKE TSLACKT ADJU S TEE.

7 Edward LeeBowemMcCombCity, Miss.

Application February-20, 1946, Serial No.1 648,995

' va Claims. I (01. Ilse-+198) ,Ihisiinvention:relates: tesanaiautoma'tic slack. adiuster ionrailroad; car ale-brakes...

Theprincipal obj ectotthis. invention is to, provide a slack adjuster yof gthezcharacter described which automatically adjusts brake travel to the limits set yf d ral lawinamelyrhetween;7".and 9". The way this isidenettqdayais :to-adjust the brakes by hand. 1 In consequence, there are periods between adjusting operations during which. the :brake travel. dangerously a proaches the 7 maximum l mit:. set,- hy Eederal law a at times-actually exceeds" it. .Ihe; present construction is designedto adjust-the.traveliautomatically scthat as :soon. as=-the maximumilimit is an: proachedanadiustment is immediately and-auto mati allv-made. 1 .I'heeadvantages oi such. construction are obvious v I Anotherlobiect of. the presentv invention. is the provislonsof. an. automatic. slack adjuster as de scribed whichimay be .used in connection with standardrailroad'.equipment-.and. which .is of simple construction andjfool proof in installation and. operation.

1A,.preferrdl embodiment-of this invention is shownin the accompanying. drawing in which- Figel ls.a,plan.view of,the slack adjuster herein claimedshowing how. itis. connected tothelorak'e rodsand handbrake;

F152 is. aside view thereof;

3 is .an enlarged Iragmentary ,top view .of the main levenofthe proposed construction;

Ilia/l isasection on theline 44-4. ,of.E'ig.'"3;"

Fig.5 is an edge view. of said main leveronthe 1i11'e;5'5 'ofliigfi;

' ,Fi'ifi isa sectiononfth'e lineB-FG ofFlg'qf and Fig.1 is a view. ofthemain lever similarto that of Fig. 3. ai'ter it ,hasemove'd beyond the limits set by Federal law. 1

' Referring now particularly to, Fig. la cylinder HI is shown in whichapiston I l is mounted movably "in-response to theflow ofcompressed. air through the pipe I 2 from theconventional source of compressed air (not shown). .This cylinder ishconnected to the carframe inthe usual way Icy-means of-bracketl3. The piston-rod I5'is connected to one ,end of the main or. masterlever l6. Also connected to the piston rodl5 is. a chain I! connected to the hand. brakelrod l8.

At theother endotthe-master lever IS a brake rod-wis'ccnnectedleading tonne of thetrucks ofythe car. Intermediate said brake rod. connece tionand said piston; rod. connection isa middle redflawhichis connectedrto-Jthe master lever [6 5by' means :of ;:a;ratchet- 1 construction hereinafter described-andwhieltisconnectedatitszother e r '2 end. to -lever.23.- Lever 231s pivoted'at 24:tothe frame of the car or to a bracket 25 affixed to the frameof the vcar and at its opposite endit-is connected to-a brake rod 26-which leads tothe other;truck of the'car. 'Ihusiar, with thesole exception ofthe. ratchet construction, the. mechanismz'herein; described is conventional.v

Reierenceto Eigse, 5iand '7 will show that themaster-leverlB-is comprised of twoearms wh ich,,for themost part, arespaced from-reach other; 'frhesetwoarms-do not move'with. respect to one another andfor alipracticalpurposes they may -;he:.:c0nsider.ed to constitutea single unit; to wit, ;the:master lever t5. The.middle--rQd--.-2Z1S cennectedibymeans. oi-a ivotedscrew member-30 to asratehetcbarrfir It willbeiseenparticularly in Hesse-and 5 that this ratchet barrpassesbes tween the two arms-constituting the-.master lever.- I B; The ratchet bar is slotted longitudinally aty32*towaccommc-date a rivet or pint33. This rivetafiixes a bracket 34 the master lever-.16 asrshowrr in Fig. 4. slidably mounted omsaid bracket by meansrof serewmember 36 is a pawl 3i.- A-tension member 38 on said-screw member 36 .tends to force the pawl against theeteeth of theratchetbar 3| to engagethe same. A'cam 39 onw aid paw1 31 is-positioned to enga eithe bracket--34 to-disengagesaid pawl-from the ratchet ban-3 I. This: actionytakes placeagainst thetensionof the springer tension member MItis-a manual operatiom .This ratchet construction, together with the twoiarms whichf-constitute the master.-lever-.l6,.

comprise part ofthe present invention and :they are not round-in standard equipment. Nonethe less,, so far the apparatus-operates in precisely the same manneras doesstandard, apparatus. a

. The-compressed air forcesthe pistonrand pise ton rod H and i5, respectively,outwardly(and causes corresponding movement of that end. of the master, leverlfito-which the piston rod i518 attached. Movement in thesamedirection ofthe middleorod- 22 ise'ffected. Movement'in the 013-]- positedirection ointhe brake rod '20 is simi arlfi efiected'sincethisbrake rod is .connectedlto the' master. lever i6 attheend oppositethat at which the piston rod .15- is connected. The. movement of. the middle rod 22 causes corresponding movement-ofthe, lever Hand the brakerodZB. illhus far there is no relative movement .betweenthe pawl 31 and the-ratchet bar 3 I.

V Referenceto Figs..-5 vand 7 will show theta secondary ,or limiting lever 53 is pivoteduatl one endto .thatzend zof. the master lever 16 .to,.whieh the brake rod-.20 is connected. Pivotal movement 3 between the secondary lever 50 and the master lever I6 is thereby provided. The free end of the secondary lever is connected by means of a chain 5| to a bracket 52 on the cylinder Hi. This chain limits the movement of the secondary lever 50 to the extent provided by law. It will be noted that secondary lever 50 is provided with a right angle projection or flange 55 through which a rod55 passes. Said rod is pivotally connected at 51 to the master lever It. At its free end it is provided with a nut 58 and intermediate said'nut and the flange member 55 is a tension member 59. This tension member abuts the nut 58 and the flange 55 and tends to urge the two levers l6 and 50 into registration with each other. When the master lever moves outwardly beyond the maximum limit provided by law as shown in Fig. '7, the chain 5| will prevent corresponding movement of the secondary lever 5|] and the master lever l6 will move out of registration with the secondary lever 50 against the action of the tension member 59.

' It will be seen in Fig. 4 that an arm 60 is connected at one end to secondary lever 50 and at the other end to a clutch member 6 This clutch member 6| is mounted on the screw member 30 which is connected at one end to the middle rod 22 and at the other end to the ratchet bar 3|. This clutch member is constructed in such manner that it will permit free movement of said rod 30 toward the right as seen in Fig. 4 but will clutch said rod 30 when said rod moves to the left. It will be recalled that a chain 5| limits the movement of the secondary lever 50 toward the right as said lever is shown in all of the figures. When the brake shoes to which the brake rods and 26 are connected become worn, there will be an excessive movement of the piston or thrust rod l5 toward the right. This will in turn cause the master lever Hi to move toward the right a correspondingly excessive distance. Since the master lever I6 is connected by means of the pawl 31 to the ratchet bar 3| and hence to the screw member 39 and the middle rod 22, such excessive movement of the master lever l6 toward the right will effect a corresponding movement of said ratchet bar, screw member and middle rod. To the extent that such latter movement is excessive there will be a slippage of the clutch member 6| with respectto the screw member 30. Incomequence, there will be a relative movement between the master lever i6 and the secondary lever 5|] as shown in Fig. '7. As has already been indicated, the limit of the movement of secondary lever 50 is determined by the length of the chain 5|.

When the brakes are released the several parts of the mechanism described in the foregoing paragraph will return to their original position. Insofar as the two levers Hi and 50 are concerned, the tension member 59 will cause these two levers to move into registration with each other from the position shown in Fig. 7 to the position shown in Figs. 3 and 4. As these two levers move into registration with each other the clutch 6| grips the screw member and moves said memher to the right with respect to the master lever I6. As a result there is relative movement between the ratchet bar 3| and the pawl 31 and'a consequent shortening of the efiective length of the middle rod 22.

The slot 10 in the ratchet bar 3| permits of this relative movement between the ratchet bar and the master lever |6. A slot ll formed at that end of middle rod 22 which engages the lever 23 is provided as a safeguard. Should the lever hang, the

4 rod will slide back over it thus preventing undesired shortening of piston travel.

It will be understood from the foregoing that what has been described is simply a preferred embodiment of the invention and that variations thereof are possible without departing from the basic principles of the invention. The key to the present invention lies in the use of a ratchet mechanism which is controlled by a, member having a predetermined limit of movement.

I claim:

1. In an automatic slack adjuster for air brakes, a compressed air cylinder, a compressed air actuated piston in said cylinder, a floating lever connected to said piston, a brake rod connected to said floating lever, a connecting rod connected to said floating lever, a dead lever connected to said connecting rod and a second brake rod connected to said dead lever, the con- 30 nection between the connecting rod and the floating lever being by means of a ratchet mechanism controlled by a clutch which operates on said connecting rod, whereby relative movement between said connecting rod and said floating lever may be efiected to shorten the operative length of said connecting rod when the piston travel exceeds a predetermined range, said clutch being itself controlled by a, third lever which is pivoted at one end to the dead lever and connected at the other end to the compressed air cylinder by means of a chain of predetermined length, said third lever being connected intermediate its ends to the clutch by means of a rod of predetermined length, said lever being also connected intermediate its ends to the dead lever by means of a spring which urges said dead lever and said third lever into registration with each other.

2. In an automatic slack adjuster for 'air brakes, a compressed air actuated piston, a floating lever connected to said piston, a brake rod connected to said floating lever, a connecting rod connected to said floating lever, a dead lever connected to said connecting rod and a second brake rod connected to said dead lever, the connection between the'connecting rod and the floating lever being by means of a ratchet mechanism controlled by a clutch which operates on said con necting rod, said clutch being connected to a tether of predetermined length to cause relative movement between said clutch and said connecting rod to the extent that said connecting rod moves beyond a predetermined range, and a compression spring acting in conjunction with said clutch for causing. relative movement of said connecting rod and said floating lever through said ratchet mechanism to shorten the operative length of said connecting rod.

3. In an automatic slack adjuster for air brakes, a compressed air actuated piston,a floating lever connected at one end to said piston, a brake rod connected to said floating lever at the opposite end thereof, a connecting rod connected at one end by means of a ratchet construction to said floating lever intermediate the two ends thereof, a dead'lever connected'to the opposite end of said connecting rod, and a second brake rod also connected to said dead lever,- a control lever, a compression spring which normally holds said control lever in registration with said floating lever, a chain of predetermined length limiting the movement of said control lever, and a clutch connected to said control lever and operating on said connecting rod, whereby travel of said floating lever beyond a predeterminedlimit will carry said floating lever- I 6 out of registration with the control lever against REFERENCES CITED the action of the compress on spring and on the return movement of said floating lever, the clutch The following r fe n r f r c rd i he will grip the connecting rot! and the compression file Of this P t! spring will cause relative inoyement between said 5 7 UNITED STATES PATENTS connecting rod and said floating lever through the e ratchet construction, bringing the control and Number Name Date floating levers back into registration with each 3871637 HlPbard May 12, 1908 other, and shortening the efiective length of said 1,937,633 Bolrault 1933 connecting rod. 10

LEE BOWEN. 

